Fungal infections Flashcards

1
Q

Define what candida, candida spp and candidiasis is

A
  • Candida” is a genus of parasitic, yeast-like fungi
  • Candida “spp.”(meaning several species of candida)•
  • “Candidiasis” – an infection of skin or mucosa caused by acandida (usually C.albicans – causes thrush)
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2
Q

Briefly talk about candida spp

A
  • Oral Candidiasis is caused by intra-oral commensal yeasts. (>80% C. albicans)
  • All oral candidal infections are opportunistic in nature.
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3
Q

Describe candida albicans

A
  • C.albicansis the most virulent Candida spp.in humans
  • A characteristic feature of C.albicans is its ability to form true hyphae.
  • These hyphae penetrate through the tissue and obtain nutrients through that
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4
Q

Describe opportunistic infections

A
  • When a harmless commensal of the oral cavity transitions to a pathogen – resulting in disease
  • Disease is a result of an imbalance between fungal virulence factors and host defenses
  • Commensal Fungi are normally kept under control through specific and non-specific host defence mechanisms
  • Competition of other micro-organisms –e.g. bacteria.
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5
Q

List 6 local predisposing factors for a candidal infection

A
  • Prostheses – changes in environmental conditions, trauma, denture usage, oral hygiene
  • Saliva quality (↓pH, ↑glucose concentrations)
  • Saliva quantity (Salivary hypofunction, Sjogren’s Syndrome, Radiotherapy, Drug Therapy)
  • Commensal Flora – e.g. modified by broad-spectrum antibiotics
  • High-Carbohydrate diet
  • Smoking
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6
Q

List 6 systemic predisposing factors for a candidal infection

A
  • Physiological – e.g. pregnancy, extremes of age - neonates/elderly
  • Endocrine disorders – e.g. Diabetes Mellitus
  • Nutritional deficiencies – e.g. Fe, Folic Acid, Vitamin B12
  • Malignancies – e.g. leukemia, agranulocytosis
  • Primary immunodeficiency – e.g.DiGeorge’s Syndrome
  • Secondary immunodeficiency – e.g.HIV, corticosteroids, anti-cancer therapies
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7
Q

List 4 ways that saliva can prevent a candidal infection

A
  • Prevents oral colonization and invasion of candida spp.
  • Removes unattached or poorly adherent candida spp
  • Inhibits candidal adhesion to host surfaces by Salivary IgA.
  • Candidacidal activity due to anti-fungal proteins (histatins, defensins, lysozymes)
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8
Q

Explain 3 ways that diabetes mellitus contributes to candidal infections

A
  • ↑ Salivary glucose levels
  • ↓ Neutrophil function due to hyperglycaemia
  • Uncontrolled DM is a major predisposing factor in Aspergillus– especially complicated by diabetic ketoacidosis.
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9
Q

Explain the significance of candida in HIV patients

A
  • Oral candidiasis is a universal finding in patients with severe cell-mediated (T-cell) immunodeficiencies – i.e.HIV/AIDS.
  • Up to 90% of HIV-infected patients develop oropharyngeal candidiasis at some point during the progression of their disease
  • Oropharyngeal candidiasis can be used as a predictor for the progress of HIV infections in affected individuals.
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10
Q

List 4 things that can lead to secondary immunosuppression

A

• Solid Organ Malignancies –e.g. Lymphoma
• Haematological
• Malignancies – e.g. Leukaemia
• Cytotoxic Chemotherapy
Topical and Systemic
• Corticosteroids and other Immunomodulatory Drugs

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11
Q

List the types of oral candidiasis

A

Primary Oral Candidiasis
• Pseudomembranous Candidiasis (Acute and Chronic)
• Erythematous Candidiasis (Acute and Chronic)
• Chronic Hyperplastic Candidiasis

Candida-associated Lesions
• Angular Cheilitis
• Median Rhomboid Glossitis
• Denture-associated Erythematous Stomatitis
• Linear Gingival Erythema

Secondary Oral Candidiasis
• Chronic Mucocutaneous
• Candidiasis

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12
Q

Describe pseudomembranous candidiasis in terms of:

  • Appearance
  • Symptoms
  • Who it occurs in
  • Places of occurrence in acute and chronic forms.
A

Description
• Also known as “oral thrush”.
• Semi-adherent, whitish, soft, creamy drop-like patches.
• They can be removed, leading to a red and slightly bleeding surface

Symptoms
• Lesions are usually asymptomatic, although sometimes patients may complain of burning and dysphagia

Who it occurs in
• The lesions may recur in patients using corticosteroids topically or by aerosol, in HIV patients or immunocompromised patients

Places of occurrence
• Acute Form: Palate, Dorsum of Tongue, Buccal Mucosa
• Chronic Form: Palate, Dorsum of Tongue, Oropharynx.

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13
Q

Explain erythematous candidiasis in terms of description and places of occurrence

A
  • May present as an acute or chronic form
  • Erythematous areas often associated with topical or systemic corticosteroid use, broad-spectrum antibiotic therapy or HIV disease
  • Painful
  • Can affect any part of the oral mucosa – but typically affects the dorsum of the tongue, palate.
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14
Q

Describe chronic hyperplastic candidiasis in terms of:

  • Appearance
  • Presentations
  • Places of occurrence
  • Histology
A

Appearance

  • Characterized by adherent white lesions ranging from small translucent to large opaque plaques.
  • Hyperplastic candidiasis lesions are not scrapable.

Presentations
Two variants
• Homogenous
• Nodular/Speckled

Places of occurrence
• Affects commissures of the mouth, less commonly on the buccal mucosa,palate, tongue
• This form may require a biopsy; as it is associated with varying grades of dysplasia

Histology:
• Parakeratosis, and hyperplastic epithelium, with inflammatory infiltrate and candidal hyphae invasion to the upper layers of the epithelium.

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15
Q

Describe angular cheilitis, list the responsible candida spp and list 6 predisposing factors

A
  • A chronic inflammatory lesion of thelabial commissures
  • May be unilateral or bilateral
  • Usually symptomatic, both skin and oral mucosa may be affected
  • May have a tendency to bleed
  • Candida spp and S. aureus are considered the cause of the lesions.
Other predisposing factors: 
• Anaemia	
• Vitamin B12 deficiency
• Immunodeficiency
• Reduced vertical dimension
• Lip-licking
• Thumb-sucking habits
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16
Q

Describe median rhomboid associated lesions

A
  • Erythematous atrophic area; “rhomboidal” in shape and located on the posterior-midline part of the dorsum of the tongue; just slightly anterior to the circumvallate papillae
  • Often asymptomatic
  • Candida sppare frequently isolated from the lesion
  • BUT – little evidence that these lesions resolve after topical anti-fungal therapy.
17
Q

Describe denture- associated erythematous stomatitis and potential causes

A
  • Chronic erythema affecting almost exclusively the palatal mucosa and alveolar ridges which are in contact with the fitting surface of a denture
  • Exact aetiopathogenesis is unknown
  • Commensal candidal overgrowth + poor oral and dental hygiene, night-time denture wear, and poor fitting dentures.
18
Q

Describe linear gingival erythema

A
  • Anon-plaque induced localized orgeneralized gingivitis found predominantly in HIV patients
  • Likely a combined bacterial and fungal opportunistic infection
  • Distinct erythematous band of 2-3mm width along the gingival margin
  • May be associated with discomfort and occasional bleeding.
  • Thought to be an HIV-associated periodontal lesion, together with necrotizing ulcerative gingivitis and periodontitis.
19
Q

Describe a secondary oral candidal lesion called chronic mucocutaneous candidiasis and list its 3 main types

A
  • Persistent or recurrent candidal infections of the oral cavity and other sites of the body.
  • Infections of the oral cavity (90%), may involve pharynx and larynx
  • Frequent cutaneous and vulvovaginal involvement.

Three main types
• Familial CMC
• Diffuse-Type CMC
• Endocrine Candidiasis Syndrome

20
Q

Describe deep fungal infections

A
  • Deep Fungal Infections are considered as systemic mycoses, but the orofacial area may also be involved with intra-oral manifestations.
  • Aspergillosis is the second most prevalent opportunistic mycotic infection after candidiasis
  • High mortality rate in the paediatric population (~85%)
  • Mucormycosis is also a common invasive fungal infection affecting immunosuppressed patients.
  • Mortality rate 20-50%
21
Q

Describe aspergillosis

A
  • Caused by a fungus called Aspergillus (e.g. Aspergillus fumigatus, Aspergillus flavus) that is present in the environment. It is usually inhaled.
  • Usually affects healthy individuals
  • May present as a non-invasive disease - “mycetoma” – a mass of fungal organisms within a body cavity – e.g. maxillary sinus.
  • Aspergillosis can develop after dental procedures – e.g.extractions, endodontic therapy involving the posterior maxillary region
  • May appear as gingival ulceration and palatal swelling with a grey to violaceous hue
22
Q

Describe mucormycosis

A
  • Caused by the fungi within the subphylum mucormycotina.
  • Infection starts in the paranasal sinuses and often spreads rapidly onto adjacent structures such as the palate, cavernous sinuses, orbits and cranium
  • Patients may have nasal obstruction, nasal discharge including blood, facial pain, headache, cellulitis, visual disturbances and seizures
  • In early stages of disease - Intra-oral examination may show swelling of the palate/maxillary alveolar process
  • If left untreated – may develop palatal ulceration, oronasal fistula, frank necrosis, and massive tissue destruction
23
Q

Describe blastomycosis

A
  • Blastomycosis is caused by Blastomyces Dermatitidis
  • Infection occurs via inhalation of spores.
  • Mainly affects the lungs, may spread to the skin, bones/joints and genitourinary tract
  • Intra-orally - may exhibit a gradually enlarging ulcer with a rolled border or an erythematous nodule with a granular/warty surface
  • May spread to the underlying maxilla/mandible
24
Q

Describe histoplasmosis

A
  • Histoplasmosis – caused by Histoplasma capsulatum
  • Inhalation of airborne spores from disrupted soil often enriched with guano
  • Most infected individuals are asymptomatic
  • Severe pulmonary disease occurs with immunocompromised patients; and may disseminate
  • Oral lesions typically appears a solitary chronic ulcer with a rolled margin
  • Oral lesions may mimic the appearance of squamous cell carcinoma.
25
Q

Describe cryptococcosis

A
  • Primary site of infection in the lungs via aspiration of airborne spores
  • Causes pulmonary cryptococcosis.
  • By haematogenous dissemination – can infect the CNS
  • Variable presentation - can present in the oral cavity as violaceous nodules of granulation tissue, swellings or ulcers
  • Diagnosis must be confirmed by microscopy and culture confirmation.